Quarter	Percent
1999-01-01	46.1
2000-01-01	43.7
2000-04-01	44
2000-07-01	44.1
2000-10-01	43.2
2001-01-01	42.5
2001-04-01	43.2
2001-07-01	43.2
2001-10-01	42.1
2002-01-01	41.5
2002-04-01	41.8
2002-07-01	41.5
2002-10-01	41.2
2003-01-01	40.8
2003-04-01	41.5
2003-07-01	41.4
2003-10-01	41.2
2004-01-01	40.6
2004-04-01	41.2
2004-07-01	42.1
2004-10-01	41.7
2005-01-01	40.6
2005-04-01	41.6
2005-07-01	42.9
2005-10-01	42.7
2006-01-01	41.8
2006-04-01	42.8
2006-07-01	44.2
2006-10-01	43.9
2007-01-01	43.8
2007-04-01	45.1
2007-07-01	46.2
2007-10-01	46.3
2008-01-01	46
2008-04-01	46.7
2008-07-01	47.6
2008-10-01	47.8
2009-01-01	47.1
2009-04-01	47.4
2009-07-01	47.8
2009-10-01	47.8
2010-01-01	46.5
2010-04-01	47.4
2010-07-01	47.8
2010-10-01	47.4
2011-01-01	47.1
2011-04-01	47.4
2011-07-01	47.4
2011-10-01	47.4
2012-01-01	47.2
2012-04-01	47.6
2012-07-01	47.8
2012-10-01	47.7
2013-01-01	46.6
2013-04-01	47.2
2013-07-01	48
2013-10-01	48.3
2014-01-01	48.1
2014-04-01	48.4
2014-07-01	49.2
2014-10-01	49.4
2015-01-01	49.0
2015-04-01	49.6
2015-07-01	50.1
2015-10-01	50.4
2016-01-01	50.2
2016-04-01	50.8
2016-07-01	50.7
2016-10-01	50.9
2017-01-01	51.2
2017-04-01	51.9
2017-07-01	51.4
2017-10-01	51.2
2018-01-01	51.5
2018-04-01	52.6